Friedrichshafen N2O4/MMH rocket engine. 29 kN. In production. Isp=324s. Upper stage engine for Ariane 5 developed 1988 - 1995. Original version could not be restarted; version for EPS L10 stage for Ariane 5V allowed multiple restarts. First flight 1996.

The Aestus rocket engine was developed at the Ottobrunn Space Propulsion Centre during the period 1988 - 1995. The first operational flight of Aestus was on 30 October 1997 on Ariane 5 flight 502. Helium pressure fed. Electromechanical gimbaled nozzle (9.5 deg).

N2O4/MMH Nitrogen tetroxide became the storable liquid propellant of choice from the late 1950's. Monomethylhydrazine (CH3NHNH2) is a storable liquid fuel that found favour in the United States for use in orbital spacecraft engines. Its advantages in comparison to UDMH are higher density and slightly higher performance. More...